NANOSIZED Fe-DOPED CERIA SAMPLES SYNTHESIZED BY FREEZE-DRYING PRECURSOR METHOD

M. MAZAN; J. MARRERO-JEREZ; P. NÚÑEZ COELLO; S.A. LARRONDO

Sevilla

Congreso; European Hydrogen Energy Conference; 2014

Solid-oxide fuel cells (SOFCs) are promising candidates for stationary power generation due to the possibility of using methane, natural gas and even biogas as fuels. Nowadays, the investigations are concern about the reduction of the operating temperature to the intermediate temperature range (500-700°C) in order to make this technology economically feasible. Reducing the operating temperature reduces the kinetics of the processes that occur at the interfaces gas / electrode increasing the associated polarization resistance. In this context, the use of nanomaterials is entirely feasible. These materials have special properties associated with the greatest contribution of the surface where it is possible to accommodate large number of defects, which can be beneficial increasing the electrochemical performance, either lowering the polarization resistance of the anode or by providing new active sites conferring resistance to coke formation, sulfur poisoning, etc. Many materials have been tested as anodes with different structures (spinels, pyrochloric, perovskite, etc.). However, CeO2-based materials with fluorite structure appear to be the most promising because the resistance to coke formation, their ability to oxidize the carbon that may be formed in reactions with hydrocarbons​​ [1-4]. Despite the good characteristics mentioned, these materials have poor electronic conductivity and morphological stability. Doping with aliovalent cations with higher ionic radius, like Gd3+  and with isovalent cations with lower ionic radius, like Zr4+, has been intensively studied. Therefore, it is interesting to study the effect of doping with an aliovalent cation, like Fe3+, with a lower ionic radius, on the physicochemical properties with the objective to develop ceria-based materials with structural and redox properties appropriated for electrocatalytic application. In this work the synthesis of nanosized Ce1-xFexO2-d mixed oxides, with x = 0, 0.1 and 0.2, by the freeze-drying precursor method is presented. The so-obtained solids were characterized by Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD), Physisorption of Nitrogen at its normal boiling point (77 K) and Temperature Programmed reduction (TPR) with hydrogen. The influence of the iron content in the physicochemical properties is studied.